An example of conventional X-ray radiation sources is one disclosed in Patent Literature 1. In this conventional structure, an X-ray tube, a high voltage generation module, and the like are incorporated into a housing having an X-ray emission window, while the X-ray tube is brought into contact with and secured to a mount disposed near the X-ray emission window. In an X-ray generator disclosed in Patent Literature 2, on the other hand, a flange provided about an output window in an X-ray tube is brought into contact with and secured to an inner wall surface of a housing.